Estimates of growth and comparisons of growth rates determined from length- and age-based models for populations of purple wrasse (Notolabrus fucicola)

Growth of a temperate reefa-ssociated fish, the purple wrasse (Notolabrus fucicola), was examined from two sites on the east coast of Tasmania by using age- and length-based models. Models based on the von Bertalanffy growth function, in the standard and a reparameterized form, were constructed by using otolith-derived age estimates. Growth trajectories from tag-recaptures were used to construct length-based growth models derived from the GROTAG model, in turn a reparameterization of the Fabens model. Likelihood ratio tests (LRTs) determined the optimal parameterization of the GROTAG model, including estimators of individual growth variability, seasonal growth, measurement error, and outliers for each data set. Growth models and parameter estimates were compared by bootstrap confidence intervals, LRTs, and randomization tests and plots of bootstrap parameter estimates. The relative merit of these methods for comparing models and parameters was evaluated; LRTs combined with bootstrapping and randomization tests provided the most insight into the relationships between parameter estimates. Significant differences in growth of purple wrasse were found between sites in both length- and age-based models. A significant difference in the peak growth season was found between sites, and a large difference in growth rate between sexes was found at one site with the use of length-based models

A Note On Independent Sets In Graphs With Large Minimum Degree and Small Cliques

Graphs with large minimum degree containing no copy of a clique on r vertices (Kr) must contain relatively large independent sets. A classical result of Andrásfai, Erdös, and Sós implies that Kr-free graphs G with degree larger than ((3r − 7)/(3r − 4))|V(G)| must be (r − 1)-partite. An obvious consequence of this result is that the same degree threshold implies an independent set of order (1/(r − 1))|V(G)|. The following paper provides improved bounds on the minimum degree which would imply the same conclusion. This problem was first considered by Brandt, and we provide improvements over these initial results for r \u3e 5

Testing heterogeneous anchoring and shift effect in double-bounded models: The case of recreational fishing in Tasmania

This paper explores the extent and nature of anchoring and shift effects in a double-bounded contingent valuation of recreational fishing in Tasmania’s inshore saltwater fishery. In particular we model the situation where respondents, when answering the second valuation question, evaluate the bid amount partly with reference to the size of the first bid amount. The estimates of the coefficients and mean WTP for a day of fishing are compared across different contingent valuation models, including a single-bounded model, a conventional double-bounded model and models that control anchoring and exogenous shift effects in both homogeneous and heterogeneous forms. Overall we find consistent evidence of anchoring, but mixed evidence of a shift effect. Results show that both males and females anchor in the same way, but that respondents who have a mainstream view of what recreational fishing represents anchor more strongly than those whose view of fishing is not mainstream. The estimated mean WTP for a day’s recreational fishing is consistently higher in all models which account for bias in responses than in either the single-bounded or double-bounded models. We indicate the possibility that anchoring behaviour may be more complex than is captured in our models and suggest that this needs to be addressed if the results of contingent valuations are to reliably inform resource allocation decisions and recreational fishing management.Contingent valuation, anchoring bias, shift effect, heterogeneity, recreational fishing, Environmental Economics and Policy, C35, Q26,

Testing heterogeneous anchoring and shift effect in double-bounded models: The case of recreational fishing in Tasmania

This paper explores the extent and nature of anchoring and shift effects in a double-bounded contingent valuation of recreational fishing in Tasmania’s inshore saltwater fishery. In particular we model the situation where respondents, when answering the second valuation question, evaluate the bid amount partly with reference to the size of the first bid amount. The estimates of the coefficients and mean WTP for a day of fishing are compared across different contingent valuation models, including a single-bounded model, a conventional double-bounded model and models that control anchoring and exogenous shift effects in both homogeneous and heterogeneous forms. Overall we find consistent evidence of anchoring, but mixed evidence of a shift effect. Results show that both males and females anchor in the same way, but that respondents who have a mainstream view of what recreational fishing represents anchor more strongly than those whose view of fishing is not mainstream. The estimated mean WTP for a day’s recreational fishing is consistently higher in all models which account for bias in responses than in either the single-bounded or double-bounded models. We indicate the possibility that anchoring behaviour may be more complex than is captured in our models and suggest that this needs to be addressed if the results of contingent valuations are to reliably inform resource allocation decisions and recreational fishing management.Contingent valuation, anchoring bias, shift effect, heterogeneity, recreational fishing, Environmental Economics and Policy, C35, Q26,

Independent Dominating Sets In Triangle-Free Graphs

The independent domination number of a graph is the smallest cardinality of an independent set that dominates the graph. In this paper we consider the independent domination number of triangle-free graphs. We improve several of the known bounds as a function of the order and minimum degree, thereby answering conjectures of Haviland

On the Independent Domination Number of Regular Graphs

A set S of vertices in a graph G is an independent dominating set of G if S is an independent set and every vertex not in S is adjacent to a vertex in S. In this paper, we consider questions about independent domination in regular graphs

Age validation, growth modeling, and mortality estimates for striped trumpeter (Latris lineata) from southeastern Australia: making the most of patchy data

Age estimates for striped trumpeter (Latris lineata) from Tasmanian waters were produced by counting annuli on the transverse section of sagittal otoliths and were validated by comparison of growth with known-age individuals and modal progression of a strong recruitment pulse. Estimated ages ranged from one to 43 years; fast growth rates were observed for the first five years. Minimal sexual dimorphism was shown to exist between length, weight, and growth characteristics of striped trumpeter. Seasonal growth variability was strong in individuals up to at least age four, and growth rates peaked approximately one month after the observed peak in sea surface temperature. A modified two-phase von Bertalanffy growth function was fitted to the length-at-age data, and the transition between growth phases was linked to apparent changes in physiological and life history traits, including offshore movement as fish approach maturity. The two-phase curve was found to represent the mean length at age in the data better than the standard von Bertalanffy growth function. Total mortality was estimated by using catch curve analysis based on the standard and two-phase von Bertalanffy growth functions, and estimates of natural mortality were calculated by using two empirical models, one based on longevity and the other based on the parameters L∞ and k from both growth functions. The interactions between an inshore gillnet fishery targeting predominately juveniles and an offshore hook fishery targeting predominately adults highlight the need to use a precautionary approach when developing harvest strategies

Leptin in Teleost Fishes: An Argument for Comparative Study

All organisms face tradeoffs with regard to how limited energy resources should be invested. When is it most favorable to grow, to reproduce, how much lipid should be allocated to storage in preparation for a period of limited resources (e.g., winter), instead of being used for growth or maturation? These are a few of the high consequence fitness “decisions” that represent the balance between energy acquisition and allocation. Indeed, for animals to make favorable decisions about when to grow, eat, or reproduce, they must integrate signals among the systems responsible for energy acquisition, storage, and demand. We make the argument that leptin signaling is a likely candidate for an integrating system. Great progress has been made understanding the leptin system in mammals, however our understanding in fishes has been hampered by difficulty in cloning fish orthologs of mammalian proteins and (we assert), underutilization of the comparative approach